1. Field of the Invention
The present invention relates to a steering wheel with an air bag unit.
2. Description of the Related Art
In the steering wheel with an air bag unit, it is generally desired to lighten the steering wheel itself since the air bag unit is relatively heavy (4 kg, for instance). Furthermore, when visibility is considered, it is required that spoke portions of the steering wheel be disposed as close to the driver as possible to secure a sufficient field of vision for the driver.
To lighten the steering wheel, the ring core of the wheel may be constructed hollow or be of a reduced diameter. To secure a sufficient field of vision, it is possible to arrange the spoke portions of the steering wheel so that among the spans of the ring portion which are supported by adjacent spoke portions, the part of the ring portion disposed nearest the vehicles windshield (front) has the largest span equal to or larger than about 1/2 of the circumference of the ring portion.
Such a steering wheel with an air bag unit is, however, liable to fail to sustain a load when the air bag is expanded. This is because in this event the air bag unit is usually subjected to an upwardly forward component of force, and hence a relatively large load is applied to the front portion of the ring portion of the steering wheel (Japanese Patent Unexamined Publication 62-234762).